Interchangeable lens camera, camera body, lens unit, and busy signal control method

ABSTRACT

An aspect of the present invention provides an interchangeable lens camera having a camera body and a lens unit that is freely attachable and detachable to the camera body. In the interchangeable lens camera, a communications unit in the camera body sends via communications terminals (MT_MOSI and MT_MISO) an INTR_BUSY control instruction that instructs whether to make notification with a busy signal (INTR_BUSY signal) for any operation out of a plurality of types of operations that can be executed, and the lens unit or camera body communications unit sets the busy signal (INTR_BUSY) to an ON state (low level) only during the period of operation of the type indicated by the INTR_BUSY control instruction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application and claims the prioritybenefit under 35 U.S.C. §120 of PCT Application No. PCT/JP2012/082029filed on Dec. 11, 2012 which application designates the U.S., and alsoclaims the priority benefit under 35 U.S.C. §119 of Japanese PatentApplication No. 2011-289517 filed on Dec. 28, 2011, which applicationsare all hereby incorporated by reference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an interchangeable lens camera with aninterchangeable lens unit having a taking lens, a camera body, the lensunit, and a busy signal control method.

2. Description of the Related Art

Interchangeable lens cameras including a camera body to and from which alens unit with a taking lens is attachable and detachable have beenwidely available. General examples of an interchangeable lens camera area single-lens reflex camera including a reflective mirror which reflectsincident light of the lens unit for introduction to an optical viewfinder, and a mirrorless single-lens reflex camera from which thereflective mirror is omitted. Also, in addition to an interchangeablelens camera having an image pickup device provided to the camera body,an interchangeable lens camera having an image pickup device to the lensunit has been known.

PTL 1 discloses the structure of an interchangeable lens camera with alens unit attachable to and detachable from a camera body, where acontrol signal is transmitted from the camera body to the lens unit.

PTL 2 discloses the structure of an interchangeable lens camera with alens unit (accessory) attachable to and detachable from the camera body,where a clock signal line for the lens unit to synchronize with thecamera body for communication is set at a Low level, thereby notifyingthe camera body of a busy state.

CITATION LIST Patent Literature

PTL 1: Japanese Patent Application Laid-Open No. 2-149073

PTL 2: Japanese Patent Application Laid-Open No. 6-3582

SUMMARY OF THE INVENTION

However, when the camera body and the lens unit each notify itscounterpart of a busy state, it is difficult to efficiently confirm thebusy state without wasteful communications.

PTL 1 merely discloses that a control signal is transmitted from thecamera body to the lens unit. When an inquiry about a busy state and aresponse indicating whether the state is busy are made by using datacommunications as described in PTL 1, such an inquiry and response arerepeated many times during a busy period, leading to wastefulcommunications.

Moreover, while it can be thought as described in PTL 2 that anotification of a busy state is made at a specific signal level (forexample, a Low level) of a signal line, it is merely possible to fixedlynotify a busy state of a predetermined specific operation. If the numberof types of operation increases, a plurality of busy signal terminalsare required to be provided to the camera body and the lens unit, andalso the load of monitoring on a busy notification receiving sideincreases.

The present invention is made in view of these circumstances, and has anobject of providing an interchangeable lens camera, camera body, lensunit, and busy signal control method capable of efficiently confirming abusy state without wasteful communications even if a plurality of typesof operation can be performed.

The present invention provides an interchangeable lens camera includinga camera body and a lens unit attachable to and detachable from thecamera body, wherein each of the camera body and the lens unit includesa communication signal terminal for instruction from the camera body tothe lens unit, busy signal terminals for a busy signal indicatingwhether now is during a period of an operation, and a communicating partwhich performs communications via the communication signal terminal andthe busy signal terminal, the communicating part of the camera bodytransmits via the communication signal terminal to the lens unit a busysignal control instruction that can indicate a type of an operation thatcan be performed by the lens unit and indicates a type of an operationof a notification target of the busy signal, and the communicating partof the lens unit sets the busy signal to an ON state only during theoperation of the type indicated by the busy signal control instruction.

According to the present invention, compared with the case in which aninquiry about a busy state and response are repeated in datacommunications, it is not required to repeat a busy inquiry and aresponse many times by using a busy signal indicating that now is duringoperation. Also, compared with the case in which a busy notification ismade only for a predetermined fixed operation by simply using a busysignal, any type of an operation of a notification target of the busysignal is indicated by a busy signal control instruction, therebyselectively and efficiently monitoring a necessary operation only withthe paired busy signal terminals provided to the camera body and thelens unit.

In an embodiment, the lens unit has a driven member and a driving partwhich drives the driven member, and at initial position driving ofdriving the driven member by the driving part to an initially setposition, with the busy signal control instruction not received from thecamera body, the communicating part of the lens unit sets the busysignal to an ON state during a period of the initial position driving,and sets the busy signal to an OFF state when the initial positiondriving ends. That is, by making a busy notification without using abusy signal control instruction normally used, the lens unit can quicklydrive the driven member to the initially set position without waitingfor the busy signal control instruction.

In an embodiment, the communicating unit of the lens unit retains thetype of the operation indicated by the busy signal control instructionin the memory and, every time the operation of the type retained in thememory is performed, the communicating unit of the lens unit sets thebusy signal corresponding to the operation of the type retained in thememory to an ON state until an operation of another type is indicated bythe busy signal control instruction or until an instruction of the typeof the operation indicated by the busy signal control instruction iscancelled. That is, the busy signal control instruction is not requiredto be transmitted for each operation, and therefore a wasteful busysignal control instruction is omitted.

In an embodiment, when operations of a plurality of types are specifiedby the busy signal control instruction, the communicating part of thelens unit sets the busy signal to an ON state when each of theoperations of the plurality of types is started and sets the busy signalto an OFF state when each of the operations of the plurality of typesends.

In an embodiment, when operations of a plurality of types are specifiedby the busy signal control instruction, the communicating part of thelens unit sets the busy signal to an ON state when a first operationamong the operations of the plurality of types is started and sets thebusy signal to an OFF state when all of the operations end.

In an embodiment, the lens unit has driving parts which drive a zoomlens, a focus lens, and an iris, and the communicating part of the lensunit sets the busy signal to an ON state during a period of driving byany of the driving parts.

In an embodiment, when mutually transmitting the busy signal controlinstruction that can indicate a type of an operation that can beperformed by the lens unit or the camera body and indicates a type of anoperation of a notification target of the busy signal, the communicatingpart of the camera body transmits to the lens unit the busy signalcontrol instruction including information indicating that a controllerof the busy signal is the camera body when an operation to be performedby the camera body is selected as the notification target of the busysignal, and transmits to the lens unit the busy signal controlinstruction including information indicating that the controller of thebusy signal is the lens unit when an operation to be performed by thelens unit is selected as the notification target of the busy signal.

In an embodiment, the camera body has an image pickup device, and thecommunicating part of the camera body sets the busy signal ON during anexposure period of the image pickup device.

Note in the present invention that “operation” for instruction with thebusy signal control instruction is not restricted to a mechanicaloperation of the focus lens, the zoom lens, the iris, or the like, butmay be an electrical operation such as exposure of the image pickupdevice, signal processing, read and write of a storage device, or thelike, or a software processing operation such as a computing process.

According to the present invention, when the camera body and the lensunit each notify its counterpart that now is during a period of anoperation, a busy state can be efficiently confirmed without wastefulcommunication.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a front outer view of an interchangeablelens camera according to an embodiment of the present invention.

FIG. 2 is a block diagram of an entire structure of the interchangeablelens camera of FIG. 1.

FIG. 3 is a descriptive diagram of a body mount (body-side mount part),a lens mount (lens-side mount part), and their peripheral parts.

FIG. 4 is a timing chart of an example of a busy signal control process.

FIG. 5 is a flowchart of an example of the busy signal control processin a lens unit.

FIG. 6 is a timing chart of an example of change in voltage level ofeach terminal when a camera body is powered ON.

FIG. 7 is a flowchart of an example of the busy signal control processin a camera body.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention are described in detail belowaccording to the attached drawings.

FIG. 1 is a perspective view of a front outer view of an interchangeablelens camera (hereinafter refer to a “camera”) according to an embodimentof the present invention.

As depicted in FIG. 1, a camera 10 of the present embodiment includes alens unit 100 and a camera body 200. The lens unit 100 includes a lensmount 160 (lens-side mount part) attachable to and detachable from abody mount 260 (body-side mount part), which will be described furtherbelow, of the camera body 200. The lens unit 100 of this example is in acylindrical shape, and has the lens mount 160 formed at an end of thelens unit 100. The camera body 200 includes a body mount 260 to and fromwhich the lens mount 160 of the lens unit 100 is attachable anddetachable. The camera body 200 of this example is in a box shape, andhas the body mount 260 formed approximately at the center of the frontsurface of the camera body 200. With the lens mount 160 of the lens unit100 mounted on the body mount 260 of the camera body 200, the lens unit100 is attachably and detachably mounted on the camera body 200.

The lens mount 160 and the body mount 260 are each provided with aplurality of terminals as contacts. While only terminals 260 a of thebody mount 260 are depicted in FIG. 1, terminals are provided also tothe lens mount 160. When the lens mount 160 is mounted on the body mount260, the terminals of the lens mount 160 and the body mount 260 abut oneach other for conduction. In this example, the plurality of terminals260 a of the body mount 260 and the plurality of terminals of the lensmount 160 are provided along a circumferential direction of the lensunit 100.

On the front surface of the camera body 200, a flash 20 (built-instrobe) for radiating a subject with illumination light is provided. Onthe upper surface of the camera body 200, a release button 22, a powersupply switch 24, and a dial 26 are provided. Also, on the back surfaceof the camera body 200 not depicted, a monitor (216 in FIG. 2), whichwill be described further below, and various buttons are provided.

The release button 22 functions as photographing instruction input meansfor inputting a photographing instruction, and is configured of a typeof so-called two steps, “halfway press” and “full press”. In the camera10, with the release button 22 pressed halfway down, AE (AutomaticExposure) and AF (Auto Focus) are caused to function. With a full press,photographing is performed.

The power supply switch 24 is configured of a slide-type switch in thisexample. With a slide operation of the power supply switch 24, thecamera body 200 is powered ON/OFF. Note that the power supply switch 24is not restricted to one of a slide operation type, and the placementlocation is not restrictive, either. For example, the power supplyswitch 24 may be placed on the back surface of the camera body 200.

The dial 26 is a rotation-type operation member, and functions as meansfor switching the mode of the camera 10. The camera 10 can be set to a“photographing mode” in which an image of a subject is recorded byphotographing the subject with a rotating operation of the dial 26 or toa “replay mode” in which the recorded image is replayed.

FIG. 2 is a block diagram of an entire structure of the camera 10.

The lens unit 100 includes a photographing optical system 102 (a zoomlens 104, a focus lens 106, and an iris 108), a zoom lens control part114, a focus lens control part 116, an iris control part 118, a lens CPU120, a flash ROM 126, a lens communicating part 150 (lens-sidecommunicating part), and the lens mount 160 (lens-side mount part).

The photographing optical system 102 has the zoom lens 104, the focuslens 106, and the iris 108. The zoom lens control part 114 controls theposition of the zoom lens 104 by following an instruction from the lensCPU 120. The focus lens control part 116 controls the position of thefocus lens 106 by following an instruction from the lens CPU 120. Theiris control part 118 controls an opening area of the iris 108 byfollowing an instruction from the lens CPU 120.

The lens CPU 120 is a CPU (Central Processing Unit) of the lens unit100, and has a ROM 124 and a RAM 122 incorporated therein.

The flash ROM 126 is a non-volatile memory for storing a program or thelike downloaded from the camera body 200.

The lens CPU 120 controls each part of the lens unit 100 by following acontrol program stored in the ROM 124 or the flash ROM 126, with the RAM122 taken as a work area.

With the lens mount 160 mounted on the body mount 260 of the camera body200, the lens communicating part 150 communicates with the camera body200 via a plurality of signal terminals (lens-side signal terminal),which will be described further below, provided on the lens mount 160.

The camera body 200 includes an image pickup device (MOS type or CCDtype) 201, an image-pickup-device control part 202, an analog signalprocessing part 203, an A/D converter 204, an image input controller205, a digital signal processing part 206, a RAM 207, acompression/decompression processing part 208, a media control part 210,a memory card 212, a display control part 214, a monitor 216, a body CPU220 (body control part), an operating part 222, a timepiece part 224, aflash ROM 226, a ROM 228, an AF detecting part 230, an AE/AWB detectingpart 232, a power supply control part 240, a battery 242 (power supply),a flash control part 246, a body communicating part 250 (lens-sidecommunicating part), and the body mount 260 (body-side mount part).

The image pickup device 201 is configured of an image sensor forphotographing a subject. An optical image of the subject formed by thephotographing optical system 102 of the lens unit 100 on alight-receiving surface of the image pickup device 201 is converted bythe image pickup device 201 to an electrical signal. Examples of theimage pickup device 201 include a MOS (Meta Oxide Semiconductor)-typeimage sensor and a CCD (Charge Coupled Device)-type image sensor.

The image-pickup-device control part 202 controls photographing timingof the image pickup device 201, exposure time, and others by followingan instruction from the body CPU 220.

The analog signal processing part 203 performs various analog signalprocesses on an analog image signal obtained by photographing a subjectwith the image pickup device 201. The analog signal processing part 203of this example is configured to include a sampling hold circuit, acolor separation circuit, a gain adjustment circuit, and others.

The A/D converter 204 converts the analog image signal outputted fromthe analog signal processing part 203 to a digital image signal.

The image input controller 205 temporarily stores the digital imagesignal outputted from the A/D converter 204 in the RAM 207 as imagedata. Note that when the image pickup device 201 is a MOS-type imagepickup device, the A/D converter 204 is usually incorporated in theimage pickup device 201.

The digital signal processing part 206 performs various digital signalprocesses on image data stored in the RAM 207. The digital signalprocessing part 206 of this example is configured to include a luminanceand color-difference signal generation circuit, a gamma correctioncircuit, a sharpness correction circuit, a contrast correction circuit,a white balance correction circuit, and others.

The compression/decompression processing part 208 performs a compressionprocess on non-compressed image data stored in the RAM 207. Also, thecompression/decompression processing part 208 performs a decompressionprocess on compressed image data.

The media control part 210 performs control of recording the image datacompressed by the compression/decompression processing part 208 in thememory card 212. Also, the media control part 210 performs control ofreading compressed image data from the memory card 212.

The display control part 214 performs control of causing non-compresseddata stored in the RAM 207 to be displayed on the monitor 216.

The monitor 216 is configured of a display device such as, for example,a liquid-crystal display device or an organic EL display device.

When a live view image is displayed on the monitor 216, digital imagesignals successively generated by the digital signal processing part 206are temporarily stored in the RAM 207. The display control part 214converts the digital image signals temporarily stored in the RAM 207 toa signal format for display, and sequentially outputs the resultantsignals to the monitor 216. With this, the photographing image isdisplayed on the monitor 216 in a real time manner, and photographing asusing the monitor 216 as an electronic view finder can be performed.

When photographing of a subject and recording of a subject image areperformed, the release button 22 is pressed halfway down, therebyperforming AE control and AF control under the control of the body CPU220, and photographing is performed with a full press. The imageobtained by photographing is compressed in a predetermined compressionformat (for example, JPEG format) by the compression/decompressionprocessing part 208. The compressed image data is provided with anecessary accessary information such as an photographing date and timeand photographing conditions to be formed as an image file, and is thenstored in the memory card 212 via the media control part 210.

The body CPU 220 performs centralized control over the operation of theentire camera 10. Also, the body CPU 220 forms a mount determining partwhich determines whether the lens unit 100 is mounted on the body mount260. A lens mount determining process by the body CPU 220 will bedescribed in detail further below.

The operating part 222 is configured to include the release button 22,the power supply switch 24, and the dial 26 depicted in FIG. 1. The bodyCPU 220 controls each part of the camera 10 based on an input from theoperating unit 222 or the like.

The timepiece part 224 measures time as a timer based on an instructionfrom the body CPU 220. Also, the timepiece part 224 measures currentyear, month, day, and time as a calendar.

The flash ROM 226 is a readable and writable non-volatile memory, andstores setting information.

In the ROM 228, the control program to be executed by the body CPU 220and various data required for control are recorded. The body CPU 220controls each part of the camera 10 by following the control programstored in the ROM 228, with the RAM 207 taken as a work area.

The AF detecting part 230 calculates a numerical value required for AF(auto focus) control based on a digital image signal. In the case ofso-called contrast AF, for example, an integrated value (focusevaluation value) of high-frequency components of G signal in apredetermined AF area is calculated. The body CPU 220 moves the focuslens 106 to a position where the focus evaluation value is maximum. Notethat AF is not restricted to contrast AF. For example, AF of aphase-difference type may be performed.

The AE/AWB detecting part 232 calculates a numerical value required froAE (auto exposure) control and AWB (auto white balance) control based ona digital image signal. The body CPU 220 calculates brightness (subjectluminance) of the subject based on the numerical value obtained from theAE/AWB detecting part 232, and determines an iris value and a shutterspeed from a predetermined program diagram.

The power supply control part 240 provides each part of the camera body200 with a power supply voltage supplied from the battery 242 byfollowing an instruction from the body CPU 220. Also, the power supplycontrol part 240 provides each part of the lens unit 100 with a powersupply voltage supplied from the battery 242 via the body mount 260 andthe lens mount 160.

The lens power supply switch 244 switches between ON/OFF and the levelof a power supply voltage to be supplied to the lens unit 100 via thebody mount 260 and the lens mount 160 by following an instruction fromthe body CPU 220.

The flash control part 246 controls light emission of the flash 20 byfollowing an instruction from the body CPU 220.

The body communicating part 250 performs signal transmission andreception (communications) between the body mount 260 and the lenscommunicating part 150 of the lens unit 100 connected via the lens mount160 by following an instruction from the body CPU 220. On the otherhand, by following an instruction from the lens CPU 120, the lenscommunicating part 150 performs signal transmission and reception(communications) between the lens mount 160 and the body communicatingpart 250 of the camera body 200 connected via the body mount 260.

[Embodiment of Mount Part]

FIG. 3 depicts the body mount 260, the lens mount 160, and theirperipheral parts. With the lens mount 160 mounted on the body mount 260,the plurality of terminals (in this example, a number “01” to a number“10” of FIG. 3) of the body mount 260 respectively abut on the pluralityof terminals of the lens mount 160.

A first terminal (+5 V terminal) of the body mount 260 is a firstbody-side power supply terminal for providing a voltage of +5 V of thebattery 242 from the camera body 200 to the lens unit 100. A firstterminal (+5 V terminal) of the body mount 260 is connected to the powersupply control part 240 and the battery 242 via the lens power supplyswitch 244.

A second terminal (GND terminal) and a third terminal (DGND terminal) ofthe body mount 260 are body-side ground terminals for providing 0 V(ground voltage) from the camera body 200 to the lens unit 100. Thesecond terminal and the third terminal are connected to the ground ofthe camera body 200.

A fourth terminal to an eighth terminal of the body mount 260 are aplurality of body-side signal terminals for transmitting and receiving asignal to and from the lens unit 100.

The fourth terminal (INTR_BUSY signal terminal) of the body mount 260 isa body-side busy signal terminal for notifying the camera body 200 fromthe lens unit 100 whether the lens unit 100 is during a period of aspecific operation. By using this fourth terminal, the lens unit 100 maybe notified from the camera body 200 of a specific operation period ofthe camera body 200. In this example, a High level (high potential)indicates that the relevant part is during a non-operation period and aLow level (low potential) indicates that the relevant part is duringoperation (in a busy state).

The fifth terminal (VSYNC signal terminal) of the body mount 260 is abody-side signal terminal for synchronization between the camera body200 and the lens unit 100.

The sixth terminal (MT_MOSI signal terminal), the seventh terminal(MT_SCK signal terminal), and the eighth terminal (MT_SIMO signalterminal) of the body mount 260 are body-side communication signalterminals for serial communications between the camera body 200 and thelens unit 100. A MT_MOSI signal is a signal outputted from the camerabody 200 as a master and inputted to the lens unit 100 as a slave. AMT_SCK signal is a clock signal provided from the camera body 200 as amaster to the lens unit 100 as a slave. The MT_SIMO signal is a signaloutputted from the lens unit 100 as a slave and inputted to the camerabody 200 as a master.

A ninth terminal (LENS_DET terminal) of the body mount 260 is abody-side terminal dedicated for detection of the lens unit 100. In thisexample, a High level (high potential) indicates that the LENS_DETterminal of the body mount 260 and the LENS_DET terminal of the lensmount 160 are in a non-abutting state (non-mount state), and a Low level(low potential) indicates that the LENS_DET terminal of the body mount260 and the LENS_DET terminal of the lens mount 160 are in an abuttingstate (mount state).

A tenth terminal (+3.3 V terminal) of the body mount 260 is a secondbody-side power supply terminal for providing a voltage of +3.3 V of thebattery 242 from the camera body 200 to the lens unit 100.

The ninth terminal (LENS_DET terminal) of the body mount 260 isconnected to the power supply control unit 240 and the battery 242 via afirst pull-up resistor R1. Also, among the plurality of signal terminalsfor signal transmission and reception (communications) of the body mount260 (the fourth terminal to the eighth terminals), the sixth terminal(MT_MOSI signal terminal) is connected to the battery 242 via a secondpull-up resistor R2 and the lens power supply switch 244. In thisexample, the first pull-up resistor R1 and the second pull-up resistorR2 have a resistance value of 220 k ohm.

The second pull-up resistor R2 is connected to the lens power supplyswitch 244. With the lens power supply switch 244 turned OFF (in anon-powered-up state of the lens unit 100), the sixth terminal (MT_MOSIsignal terminal) is not pulled up. With the lens power supply switch 244turned ON by the body CPU 220 (in a powered-up state of the lens unit100), the sixth terminal (MT_MOSI signal terminal) is pulled up. Thatis, the voltage of the sixth terminal (MT_MOSI signal terminal) of thelens unit 100 does not become at a high level only with the power supplyswitch 24 of the camera body 200 turned ON, and it was not until thelens power supply switch 244 is turned ON by the body CPU 220 that thevoltage of the sixth terminal (MT_MOSI signal terminal) of the lens unit100 becomes at a high level. With this, an erroneous operation of a LensMC 152 (integrated circuit) on a lens unit 100 side can be prevented.

Prior to pre-power-up of the lens unit 100 via a body-side power supplyterminal of the body mount 260, the body CPU 220 (mount determiningpart) of the camera body 200 takes only the ninth terminal (LENS_DETterminal) as a determination target, and determines whether the ninthterminal (LENS_DET terminal) is at a low level. When a determination ismade such that the ninth terminal (LENS_DET terminal) is at a low level,after pre-power-up of the lens unit via the body-side power supplyterminal of the body mount 260, the body CPU 220 determines whether theLENS_DET terminal and the sixth terminal (MT_MOSI signal terminal) atnon-communications are both at a low level.

The ninth terminal (LENS_DET terminal) of the lens mount 160 isconnected to the ground (the GND terminal and the DGND terminal). Also,among the plurality of signal terminals (the fourth terminal to theeighth terminal) of the lens mount 160, the sixth terminal (MT_MOSIsignal terminal) is connected to the ground via a pull-down resistor R3(in this example, 47 k ohm), which has a resistance value sufficientlysmall with respect to the pull-up resistor R2.

The body CPU 220 makes, as the mount determining part, a determinationas to whether the lens mount 160 is mounted on the body mount 260 (thatis, a determination as to whether the lens unit 100 is mounted on thecamera body 200) based on the voltage (High/Low level) of the ninthterminal (LENS_DET terminal) of the body mount 260 and the voltage(High/Low level) of a specific body-side signal terminal (in thisexample, the MT_MOSI signal terminal) at non-communications.Specifically, the body CPU 220 determines that the lens unit 100 ismounted on the body mount 260 when the voltage of the LENS_DET terminalof the camera body 200 and the voltage of the MT_MOSI signal terminal atnon-communications are both at a low level.

Also, by the lens CPU 120, a determination as to whether the lens mount160 is mounted on the body mount 260 (that is, a determination as towhether the lens unit 100 is mounted on the camera body 200) may be madebased on the voltage (High/Low level) of the ninth terminal (LENS_DETterminal) of the lens mount 160 and the voltage (High/Low level) of aspecific lens-side signal terminal (in this example, the MT_MOSI signalterminal) at non-communications. Specifically, the lens CPU 120determines that the lens unit 100 is mounted on the body mount 260 whenthe voltage of the LENS_DET terminal of the lens unit 100 and thevoltage of the MT_MOSI signal terminal at non-communications are both ata low level.

In the embodiment depicted in FIG. 3, one or more signal terminals areplaced between the MT_MOSI signal terminal of the body mount 260 (thespecific body-side signal terminal) and each of the power supplyterminals (the +5 V terminal and the +3.3 V terminal). Also, one or moresignal terminals are placed between the MT_MOSI signal terminal of thebody mount 260 (the specific body-side signal terminal) and the groundterminals GND and DGND. Furthermore, one or more signal terminals areplaced between the MT_MOSI signal terminal of the body mount 260 (thespecific body-side signal terminal) and the LENS_DET terminal dedicatedfor lens detection. As such, the MT_MOSI signal terminal for use inmount determination is placed at a position away from the power supplyterminals, the ground terminals, and the terminal dedicated for lensdetection, thereby preventing an erroneous detection due to electricshort or the like and, furthermore, improving accuracy in mountdetermination.

An ASIC 252 (integrated circuit) configuring the body communicating part250 has a terminal 254 for detecting a change (High/Low) in potential ofthe fourth terminal (hereinafter also referred to as an “INTR_BUSYsignal terminal” or a “busy signal terminal”) of the body mount 260, aterminal 255 for providing a synchronous signal to the fifth terminal(VSYNC signal terminal) of the body mount 260, an interface SPI forserial communications using the sixth to eighth terminals (hereinafterreferred to as “communication signal terminals”) of the body mount 260,a terminal 257 for detecting a change (High/Low) in potential of theninth terminal (LENS_DET terminal) of the body mount 260, and terminals258 and 259 for updating firmware of the lens unit 100.

The Lens MC 152 (integrated circuit) configuring the lens communicatingpart 150 has a terminal 154 for detecting a change (High/Low) inpotential of the fourth terminal (INTR_BUSY signal terminal) of the lensmount 160, an interface SPI for serial communications using the sixth toeighth terminals (communication signal terminals) on the lens side ofthe lens mount 160, and a terminal 158 for updating firmware of the lensunit 100.

[Example of Busy Signal Control Process]

FIG. 4 is a timing chart of an example of change in voltage level ofeach terminal of the body mount 260 and the lens mount 160.

First, from the body communicating part 250 to the lens communicatingpart 150, a first INTR_BUSY control instruction (controller: lens unit,control detail: focus motor driving) is transmitted via the MT_MOSIsignal terminal. With the first INTR_BUSY control instruction,“controller” as a subject which controls the signal level of theINTR_BUSY signal is specified as the lens unit 100, and “control detail”as a notification target by the busy signal is specified as focus motordriving. Upon receiving the instruction, the lens communicating part 150returns a response to the body communicating part 250 via the MT_MISOsignal terminal.

Next, from the body communicating part 250 to the lens communicatingpart 150, a first focus motor driving instruction is transmitted via theMT_MOSI signal terminal. For example, the instruction is such that thefocus lens is moved to a x 1 pulse position. Upon receiving theinstruction, the lens communicating part 150 returns a response to thebody communicating part 250 via the MT_MISO signal terminal.

The lens communicating part 150 sets the INTR_BUSY signal to a Low level(an ON state) while the focus lens is moved by the focus motor of thefocus lens control part 116 (during a focus motor driving period). Also,when driving ends, the lens communicating part 150 sets the INTR_BUSYsignal to a High level (an OFF state).

Next, from the body communicating part 250 to the lens communicatingpart 150, a second focus motor driving instruction is transmitted viathe MT_MOSI signal terminal. For example, the instruction is such thatthe focus lens is moved to a ×2 pulse position. Upon receiving theinstruction, the lens communicating part 150 returns a response to thebody communicating part 250 via the MT_MISO signal terminal.

The lens communicating part 150 sets the INTR_BUSY signal at a Low level(an ON state) during the focus motor driving period. Also, when drivingends, the lens communicating part 150 sets the INTR_BUSY signal at aHigh level (an OFF state).

Note in this example that a focus motor driving stop instruction istransmitted from the body communicating part 250 to the lenscommunicating part 150 via the MT_MOSI signal terminal. Upon receivingthe instruction, the lens communicating part 150 returns a response tothe body communicating part 250 via the MT_MISO signal terminal. In thisexample, at the time when driving of the focus motor stops, the lenscommunicating part 150 set the INTR_BUSY signal at a High level (an OFFstate).

Next, from the body communicating part 250 to the lens communicatingpart 150, a third focus motor driving instruction is transmitted via theMT_MOSI signal terminal. For example, the instruction is such that thefocus lens is moved to a ×3 pulse position. Upon receiving theinstruction, the lens communicating part 150 returns a response to thebody communicating part 250 via the MT_MISO signal terminal.

During the focus motor driving period, the lens communicating part 150sets the INTR_BUSY signal at a Low level (in an ON state).

Also, from the lens communicating part 150 to the body communicatingpart 250, a second INTR_BUSY control instruction (controller: camerabody, control detail: exposure period) is transmitted via the MT_MOSIsignal terminal. With the second INTR_BUSY control instruction, thecamera body 200 is specified as a “controller” as a subject whichcontrols the signal level of the INTR_BUSY signal, and exposure isspecified as a “control detail” as a notification target by a busysignal. Upon receiving the instruction, the body communicating part 250returns a response to the lens communicating part 150 via the MT_MISOsignal terminal.

The body communicating part 250 sets the INTR_BUSY signal at a Low level(an ON state) during an exposure period. Also, when driving ends, thebody communicating part 250 sets the INTR_BUSY signal at a High level(an OFF state). In this example, notification about an exposure periodwith the release button 22 fully pressed with (an S2 switch turned ON)is made by the INTR_BUSY signal.

Note that the lens unit 100 has the zoom lens control part 114, thefocus lens control part 116, and the iris control part 118 as drivingparts which drive the zoom lens 104, the focus lens 106, and the iris108, respectively. Also, the zoom lens control part 114, the focus lenscontrol part 116, and the iris control part 118 have drive motors forchanging the position of the zoom lens 104, the position of the focuslens 106, and the opening of the iris 108, respectively. The lenscommunicating part 150 sets the INTR_BUSY signal to an ON state during adrive period of the zoom lens 104 by the drive motor of the zoom lenscontrol part 114, during a drive period of the focus lens 106 by thedrive motor of the focus lens control part 116, and during a driveperiod of the iris 108 by the iris control part 118. However, theINTR_BUSY signal is set to an ON state only when the INTR_BUSY controlsignal indicates “control detail” (notification target of the busysignal). That is, the present invention is not restricted to make anotification that all of the focus lens 106, the zoom lens 104, and theiris 108 are being operated (busy), but may make a notification that atleast one of the focus lens 106, the zoom lens 104, and the iris 108 isbeing operated.

FIG. 5 is a flowchart depicting a flow of an example of the busy signalcontrol process in the lens unit 100. The process is performed by thelens CPU 120 according to a program.

First, an instruction is received by the lens communicating part 150from the body communicating part 250 via serial communications (stepS2).

Next, a response to the instruction is transmitted by the lenscommunicating part 150 to the body communicating part 250 via serialcommunications (step S4).

Next, it is determined whether the received instruction is an INTR_BUSYsignal control instruction (step S6).

When an INTR_BUSY signal control instruction is received, the INTR_BUSYsignal control instruction is stored in the RAM 122 (step S8).

Also, it is determined whether the received instruction is an operationinstruction (such as a focus motor driving instruction, a zoom motordriving instruction, or an iris motor driving instruction) (step S10).

When an operation instruction is received, it is further determinedwhether the operation is the one indicated by the INTR_BUSY signalcontrol instruction (step S12). That is, it is determined whether theoperation is included as “control detail” (notification target of thebusy signal) in the INTR_BUSY signal stored in the RAM 122. When theoperation is the one indicated by the INTR_BUSY signal controlinstruction, the INTR_BUSY signal is set at a Low level (an ON state)(step S14), the operation is started (such as focus motor driving, zoommotor driving, or iris motor driving) (step S16), and it is determinedwhether the operation ends (step S18). When the operation ends, theINTR_BUSY signal is set at a High level (an OFF state) (step S20).

In the present embodiment, the camera body 200 and the lens unit 100each include a communicating part (the body communicating part 250 andthe lens communicating part 150) which communicates via thecommunication signal terminals (the MT_MOSI signal terminal, the MT_MISOsignal terminal, and the MT_SCK signal terminal) and the INTR_BUSYsignal terminal (busy signal terminal). The body communicating part 250transmits an INTR_BUSY signal control instruction which can indicate thetype of operation executable at the lens unit 100 or the camera body 200and indicating the type of the operation of the notification target ofthe INTR_BUSY signal to the lens unit 100. The lens communicating part150 and the body communicating part 250 set the INTR_BUSY signal to anON state only during a period of operation of the type indicated by theINTR_BUSY signal control instruction.

Also in the present embodiment, the lens communicating part 150 retainsthe “controller” and the “control detail” (type of operation as anotification target of the INTR_BUSY signal) of the INTR_BUSY signalcontrol instruction in the RAM 122 (memory), and sets the INTR_BUSYsignal to an ON state every time the operation of the type retained inthe RAM 122 is performed, until another type of operation is indicatedby the INTR_BUSY signal as a “control detail”. However, the presentinvention is not restricted to this case. An instruction of the type ofoperation indicated by the INTR_BUSY signal control instruction can becancelled by serial communications, and the INTR_BUSY signal may be setto an ON state every time the operation of the type retained in the RAM122 is performed until the instruction of the type of operationindicated by the INTR_BUSY signal control instruction is cancelled.

Furthermore, while the example has been described in the presentembodiment in which, when a plurality of types of operations arespecified by the INTR_BUSY signal control instruction as a “controldetail”, the lens communicating part 150 sets the INTR_BUSY signal to aLow level (an ON state) at the time of starting each of the operationsof the plurality of type and the INTR_BUSY signal is set to a High level(an OFF state) at the end of each of the operations of the plurality oftypes, the present invention is not restricted to this case. When aplurality of types of operations are specified by the INTR_BUSY signalcontrol instruction as a “control detail”, the lens communicating part150 may set the INTR_BUSY signal to an ON state at the time of startingan initial operation among the plurality of types of operations, and mayset the INTR_BUSY signal to an OFF state at the end of the entireoperation.

Also at step S22, it is determined whether the instruction received fromthe camera body 200 is a stop instruction (such as focus motor drivingstop instruction, zoom motor driving stop instruction, or iris motordriving stop instruction). If an operation stop instruction has beenreceived, the operation is stopped (step S24). After the operation ends(Yes at step S18), the INTR_BUSY signal is set at a High level (an OFFstate) (step S20). Note that while the process flow is depicted in FIG.5 in which the end of the operation is waited for without receiving aninstruction at step S18 for convenience of description, in practice, aninstruction can be received also during operation.

[Example of Busy Signal Control when Camera Body Power Supply is TurnedON]

In the present embodiment, at the time of initial position driving inwhich a driven member (the zoom lens 104, the focus lens 106, or theiris 108) is driven by a driving part (the zoom lens control part 114,the focus lens control part 116, or the iris control part 118) whichdrives the photographing optical system 102 to an initially setposition, with an INTR_BUSY signal control instruction and aninstruction for driving a driven member not received, the lenscommunicating part 150 sets the INTR_BUSY signal at a Low level (an ONstate) during a period of initial position driving, and sets theINTR_BUSY signal at a High level (an OFF state) at the end of initialposition driving.

FIG. 6 is a timing chart of an example of change in voltage level of anASIC 252 port corresponding to a voltage level of each terminal of thebody mount 260. In a lens mount determination period P1 (t1 to t3)depicted in FIG. 6, the body CPU 220 performs a lens mount determiningprocess. At t2 of P1, pre-power-up (soft start) is performed in which amicrocurrent from the battery 242 is supplied via the body-side powersupply terminal (+5 V terminal, +3.3 V terminal) to the lens unit 100under the control of the body CPU 220. The microcurrent at pre-power-upis smaller than the current supplied to the lens unit 100 atfull-power-up, which will be described further below (for example,several tens of mA). With pre-power-up, a capacitor (omitted in thedrawings) provided on a lens unit 100 side is gradually provided withelectric charge.

When it is determined that the lens unit 100 is mounted, pre-power-up isswitched to full-power-up. That is, full-power-up is performed in whicha current (for example, 1 A) from the battery 242 and allowing the lensunit 100 to operate is supplied to the lens unit 100 via the body-sidepower supply terminal (+5 V terminal, +3.3 V terminal) under the controlof the body CPU 220.

Note that while the voltage of the body-side power supply terminal (+5 Vterminal, +3.3 V terminal) is represented at two stages for conveniencein order to make pre-power-up (staring at t2) and full-power-up(starting at t4) visually understood with ease in FIG. 6, in practice, atarget voltage at which pre-power-up reaches with microcurrent is equalto the voltage (+5 V, 3.3 V) at full-power-up.

At full-power-up, the process makes a transition to a lens boot periodP2 (t3 to t5). When a system boot of the lens unit 100 is completed, alens initialization period P3 (t5 to t7) starts. With a full powersupply voltage (+5 V, 3.3 V) supplied to the lens unit 100 via thebody-side power supply terminal (+5 V terminal, +3.3 V terminal),communications with the lens unit 100 are performed via the signalterminal (the MT_SCK signal terminal, the MT_MOSI signal terminal,MT_MISO signal terminal, the INTR_BUSY signal terminal, and the VSYNCsignal terminal).

FIG. 7 is a flowchart of an example of the lens mount determiningprocess when the camera body 200 is powered ON. This lens mountdetermining process is performed by the body CPU 220 of the camera body200 by following a program. In the following, one example of the lensmount determining process when the camera body 200 is powered ON isdescribed by using FIG. 7.

When the camera body 200 is powered ON by the power supply switch 24 (t0of FIG. 6), the body CPU 220 performs a process of starting the camerabody 200 (step S102). At step S102, the body CPU 220 initially sets eachterminal of the body mount 260. The body CPU 220 of this example turnsthe lens power supply switch 244 OFF (pre-power-off and full-power-off)and, at the same time, sets the ASIC 252 port corresponding to each ofthe INTR_BUSY signal terminal, the VSYNC signal terminal, the MT_SCKsignal terminal, the MT_MOSI signal terminal, MT_MISO signal terminal ofthe body mount 260 to high impedance (Hi-Z).

Note that when the lens mount 160 is not mounted on the body mount 260,the voltage of the LENS_DET terminal of the body mount 260 is set at aHigh level by the first pull-up resistor R1 of the camera body 200. Whenthe lens mount 160 is mounted on the body mount 260, the voltage of theLENS_DET terminal of the body mount 260 is set at a Low level, withconduction to the ground via the terminal of the lens unit 100.

Note that when the lens unit 100 is powered up with the lens mount 160not mounted on the body mount 260, the voltage of the MT_MOSI signalterminal of the body mount 260 is set at a High level by the secondpull-up resistor R2 of the camera body 200. When the lens mount 160 ismounted on the body mount 260, the MT_MOSI signal terminal of the bodymount 260 is set at a Low level by the pull-down resistor R3 of the lensunit 100 having a resistance value sufficiently smaller than that of thepull-up resistor R2.

At t1 of FIG. 6, the body CPU 220 determines whether the LENS_DETterminal of the body mount 260 is at a Low level (step S104). When theLENS_DET terminal is at a Low level, the body CPU 220 waits 5 ms or moreby using the timepiece part 224 as a wait for chattering to becomestatically determinate (step S106), and then again determine whether theLENS_DET terminal of the body mount 260 is at a Low level (step S108).

When Yes is determined at step S104 and step S108 (that is, the LENS_DETterminal is at a Low level for 5 ms or more), the body CPU 220 performspre-power-up by the lens power supply switch 244 at t2 of FIG. 6 (stepS110). With pre-power-up, the power supply voltage is increased to avoltage level allowing a polarity determination of all signal terminalto be made when the lens is mounted. Also, the ASIC 252 portcorresponding to each of the INTR_BUSY signal terminal, the VSYNC signalterminal, the MT_SCK signal terminal, and the MT_MISO signal terminal ofthe body mount 260 is at a High level.

After pre-power-up, the body CPU 220 waits for 20 ms to 30 ms by usingthe timepiece part 224 in order to establish the voltage levels of thesignal terminals (step S112).

At t3 of FIG. 6, the body CPU 220 determines whether the LENS_DETterminal and the MT_MOSI signal terminal of the body mount 260 aresimultaneously at a Low level (step S114). The body CPU 220 in thisexample makes a level determination on the LENS_DET terminal and theMT_MOSI signal terminal and simultaneously checks whether the INTR_BUSYsignal terminal, the VSYNC signal terminal, the MT_SCK signal terminal,and the MT_MISO signal terminal are at a High level.

When the LENS_DET terminal and the MT_MOSI signal terminal are both at aLow level, it is determined that the lens unit 100 is mounted, and theprocess proceeds to step S116. When at least one terminal of theLENS_DET terminal and the MT_MOSI signal terminal is at a High level, itis determined that the lens unit 100 is not mounted, and the processproceeds to step S122.

When it is determined at step S114 that the lens is not mounted, thebody CPU 220 starts detection of a High level edge (an edge of switchingfrom a Low level to a High level) of the LENS_DET terminal (step S116).The body CPU 220 of this example enables an interrupt for detecting aHigh level edge of the LENS_DET terminal by ASIC 252.

Next, the body CPU 220 clears a start NG counter (step S118). With this,the lens mount determining process is completed.

When the lens mount determining process is completed, the body CPU 220starts a lens boot process, fully powering up the lens unit 100 by thelens power supply switch 244 (step S120, t4 of FIG. 6). Withfull-power-up, a current amount allowing various signal processes and alens operation by the lens unit 100 is ensured.

Also, the body CPU 220 performs settings of each signal terminal at thetime of communications. Specifically, an interrupt for detecting a Lowlevel edge (an edge of switching from a High level to a Low level) ofthe INTR_BUSY signal is enabled, VSYNC signal output settings are made,and initial settings of the interface SPI for ASIC 252 serialcommunications are made.

In the lens boot period P2, the lens unit 100 is started (lens systemboot), allowing initial position driving of the driven member of thephotographing optical system 102. When the lens boot period P2 ends,initial position driving is started by the lens CPU 120 in which thedriven member (such as the zoom lens 104, the focus lens 106, or thelike of FIG. 2) of the lens unit 100 is moved to an initially setposition (t5 of FIG. 6). The lens communicating part 150 switches theINTR_BUSY signal from a High level to a Low level (an ON state:indicating that now is during an operation period).

Next, the process when it is detected that the lens unit 100 is notmounted at the time of power-on of the camera body 200 is described.

When determining at step S104 or S108 that the LENS_DET terminal is at aLow level (low potential), the body CPU 220 changes the operation modeto a lens non-mount mode (step S128), and makes a transition to asequence during lens powered-OFF (step S136).

Also, when determining at step 5114 that the lens unit 100 is notmounted, the body CPU 220 turns the lens power supply switch 244 OFF,thereby turning pre-power for the lens unit 100 OFF (step S122).

Next, the body CPU 220 increments the start NG counter (step S124), anddetermines whether the start NG counter has a value exceeding athreshold (in this example, “2”) (step S126).

When the start NG counter has a value equal to or smaller than thethreshold, the body CPU 220 changes the operation mode to a lensnon-mount mode, (step S128), and makes a transition to the sequenceduring lens powered-OFF (step S134).

When the start NG counter has a value exceeding the threshold, the bodyCPU 220 outputs an error message to the monitor 216 via the displaycontrol part 214 (step S130), records an error log in the flash ROM 226(step S132), clears the start NG counter (step S134), and then makes atransition to the sequence during lens powered-OFF (step S136).

As an error message, for example, “please check the lens” is displayed.The error message output may be performed as a voice output. As an errorlog, for example, “lens boot start timeout error” is recorded.

Next, initial position driving of the lens unit 100 performed by thebody CPU 220 in the lens initialization period P3 of FIG. 6 isdescribed.

In the present embodiment, to increase the speed for starting the lensunit 100, initial position driving of the lens unit 100 is automaticallyperformed simultaneously with the end of the lens boot period P2. Inthis initial position driving, the INTR_BUSY signal control instruction,which is used at normal time, is not used, and, as initial settings, thelens unit 100 is assigned as “controller” and “initial position driving”is assigned as “control detail”. Thus, the body communicating part 250which monitors the INTR_BUSY signal enables an interrupt for detecting aLow level edge of the INTR_BUSY signal at the time of full-power-up ofthe lens unit 100 as described above. The body CPU 220 regards detectionof a Low level edge of the INTR_BUSY signal as completion of lens bootand start of initial position driving of the lens unit 100.

Also, a Low level edge of the INTR_BUSY signal may not occur due to afailure of the lens unit 100 or the like. Thus, time control is startedsimultaneously with full-power-up of the lens unit 100 (t4 of FIG. 6).

The body CPU 220 uses the timer of the timepiece part 224 to monitor thepresence or absence of an interrupt of a Low level edge of the INTR_BUSYsignal. If the INTR_BUSY signal is not switched from a High level to aLow level due to a failure of the lens unit 100 or the like even thougha predetermined time (for example, 200 ms) elapses from full-power-ON,the body communicating part 250 turns the lens power supply switch 244OFF, stops full power supply to the +5 V power supply terminal and the3.3 V power supply terminal of the body mount 260, and records an errorlog in the flash ROM 226 as a lens system boot timeout error.

Also, with the busy signal control instruction and the drivinginstruction not received from the camera body 200, as initial positiondriving of the lens unit 100, the lens CPU 120 uses the driving parts(the zoom lens control part 114, the focus lens control part 116, andthe iris control part 118) to drive the driven members (the zoom lens104, the focus lens 106, and the iris 108) at respective initial settingpositions. The lens communicating part 150 sets the INTR_BUSY signal ata Low level (an ON state) during a period of initial position driving,and sets the INTR_BUSY signal at a High level (an OFF state) at the endof initial position driving (t7 of FIG. 6). With this, the body CPU 220of the camera body 200 detects, by an interrupt, a High level edge (achange from a Low level to a High level) of the INTR_BUSY signal. Notethat the body CPU 220 enables an interrupt for detecting a High leveledge of the INTR_BUSY signal at the start of the lens initializationperiod P3 where a Low level edge of the INTR_BUSY signal is detected.

When a Low edge (a change from a High level to a Low level) of theINTR_BUSY signal is detected by an interrupt in a predetermined periodfrom full-power-up, the body communicating part 250 transmits an NOPcommand by the MT_MOSI signal for serial communications to the lenscommunicating part 150. The lens communicating part 150 receiving thisNOP command transmits an NOP response by the MT_MISO signal for serialcommunications to the body communicating part 250. When this NOPresponse indicates “OK”, a lens ID and a serial number are obtained bythe body communicating part 250 and further by serial communicationswith the lens communicating part 150. When the NOP response indicates“NG”, the body communicating part 250 assumes a communication error, andperforms a communication error recovery process.

In the foregoing, while the case has been described as an example inwhich the interchangeable lens camera is an interchangeable lens camera(mirrorless single-lens reflex camera) with a reflective mirror omittedtherefrom, the present invention can be applied also to aninterchangeable lens camera including a reflective mirror. Also, thecase has been described as an example in which an image pickup device isprovided to the camera body, the present invention can be applied alsoto the case in which an image pickup device is provided to the lensunit.

Also, by way of example, FIG. 4 depicts only the case in which theINTR_BUSY signal (busy signal) and the INTR_BUSY signal controlinstruction notify that the operation is during a focus motor drivingperiod and an exposure period. However, the present invention is notparticularly restricted by this case. The INTR_BUSY signal controlinstruction can indicate, as appropriate, an operation required to bemonitored among all operations of the lens unit 100 and the camera body200 to control the signal level of the INTR_BUSY signal.

It goes without saying that the present invention is not restricted tothe examples described in the specification and the examples depicted inthe drawings and various design changes and improvements can be made ina range not deviating from the gist of the present invention.

What is claimed is:
 1. An interchangeable lens camera including a camerabody and a lens unit attachable to and detachable from the camera body,wherein each of the camera body and the lens unit includes acommunication signal terminal for instruction from the camera body tothe lens unit, paired busy signal terminals for a busy signal indicatingwhether now is during a period of an operation, and a communicating partwhich performs communications via the communication signal terminal andthe busy signal terminal, the communicating part of the camera bodytransmits via the communication signal terminal to the lens unit a busysignal control instruction that can indicate a type of an operation thatcan be performed by the lens unit and indicates a type of an operationof a notification target of the busy signal, before the busy signal isset to an ON state, and upon receiving the busy signal controlinstruction, the communicating part of the lens unit retains the type ofthe operation indicated by the busy signal control instruction in amemory, and sets the busy signal corresponding to the operation of thetype retained in the memory to an ON state only during the operation ofthe type indicated by the busy signal control instruction and every timethe operation of the type retained in the memory is performed.
 2. Theinterchangeable lens camera according to claim 1, wherein the lens unithas a driven member and a driving part which drives the driven member,and at initial position driving of driving the driven member by thedriving part to an initial position, with the busy signal controlinstruction not received from the camera body, the communicating part ofthe lens unit sets the busy signal to an ON state during a period of theinitial position driving, and sets the busy signal to an OFF state whenthe initial position driving ends.
 3. The interchangeable lens cameraaccording to claim 1, wherein every time the operation of the typeretained in the memory is performed, the communicating unit of the lensunit sets the busy signal corresponding to the operation of the typeretained in the memory to an ON state until an operation of another typeis indicated by the busy signal control instruction or until aninstruction of the type of the operation indicated by the busy signalcontrol instruction is cancelled.
 4. The interchangeable lens cameraaccording to claim 1, wherein when operations of a plurality of typesare specified by the busy signal control instruction, the communicatingpart of the lens unit sets the busy signal to an ON state when each ofthe operations of the plurality of types is started and sets the busysignal to an OFF state when each of the operations of the plurality oftypes ends.
 5. The interchangeable lens camera according to claim 1,wherein when operations of a plurality of types are specified by thebusy signal control instruction, the communicating part of the lens unitsets the busy signal to an ON state when a first operation among theoperations of the plurality of types is started and sets the busy signalto an OFF state when all of the operations end.
 6. The interchangeablelens camera according to claim 1, wherein the lens unit has drivingparts which drive a zoom lens, a focus lens, and an iris, and thecommunicating part of the lens unit sets the busy signal to an ON stateduring a period of driving by any of the driving parts.
 7. Theinterchangeable lens camera according to claim 1, wherein when mutuallytransmitting the busy signal control instruction that can indicate atype of an operation that can be performed by the lens unit or thecamera body and indicates a type of an operation of a notificationtarget of the busy signal, the communicating part of the camera bodytransmits to the lens unit the busy signal control instruction includinginformation indicating that a controller of the busy signal is thecamera body when an operation to be performed by the camera body isselected as the notification target of the busy signal, and transmits tothe lens unit the busy signal control instruction including informationindicating that the controller of the busy signal is the lens unit whenan operation to be performed by the lens unit is selected as thenotification target of the busy signal.
 8. The interchangeable lenscamera according to claim 1, wherein the camera body has an image pickupdevice, and the communicating part of the camera body sets the busysignal ON during an exposure period of the image pickup device.
 9. Thecamera body configuring the interchangeable lens camera according toclaim
 1. 10. The lens unit configuring the interchangeable lens cameraaccording to claim
 1. 11. A busy signal control method between a camerabody and a lens unit attachable to and detachable from the camera body,wherein each of the camera body and the lens unit includes acommunication signal terminal for instruction from the camera body tothe lens unit, paired busy signal terminals for a busy signal indicatingwhether now is during a period of an operation, and a communicating partwhich performs communications via the communication signal terminal andthe busy signal terminal, by the communicating part of the camera body,via the communication signal terminal, a busy signal control instructionthat can indicate a type of an operation that can be performed by thelens unit and indicates a type of an operation of a notification targetof the busy signal is transmitted to the communicating part of the lensunit before the busy signal is set to an ON state, and upon receivingthe busy signal control instruction, the communicating part of the lensunit retains the type of the operation indicated by the busy signalcontrol instruction in a memory, and sets the busy signal correspondingto the operation of the type retained in the memory to an ON state onlyduring the operation of the type indicated by the busy signal controlinstruction and every time the operation of the type retained in thememory is performed.
 12. The interchangeable lens camera according toclaim 1, wherein the communicating part of the lens unit sets the busysignal to an ON state when the communicating part of the lens unit isspecified by the busy signal control instruction as a controller thatcontrols the busy signal.
 13. The busy signal control method accordingto claim 11, wherein the communicating part of the lens unit sets thebusy signal to an ON state when the communicating part of the lens unitis specified by the busy signal control instruction as a controller thatcontrols the busy signal.